What Windows logs about USBEvery memory stick and portable disk plugged into a Windows machine is logged — serial number as well, and the hours it sat there. One appearing for the first time at 02:00 on a Sunday, days before a resignation, needs explaining.
Cloud storage and webmailTraces stay on the machine whatever the service — OneDrive, Dropbox, Google Drive, webmail in a browser. Sync databases, cached tokens, browser history, uploads that stopped halfway. Logging out and clearing up afterwards removes almost none of it.
Wiping tools and bulk deletionGetting rid of evidence usually makes more of it. You are left with the tool's name, a record of when it ran, and — the bit that generally settles matters — whatever it could not reach.
Sequence is the evidenceOn its own each of these has an innocent explanation ready and waiting. Set them against the clock — files gathered, stick inserted, upload finished, wiper run — and it stops looking like coincidence.